Production of linear nitrogen-containing polymeric materials



Patented June 27, 1950 PRODUCTION OF LINEAR NITROGEN-CON TAININGPOLYMERIC MATERIALS Harold Bates, James Wotherspoon Fisher, and EdwardWilliam Wheatley, Spondon, near Derby, England, assignors to CelaneseCorporation of America, a corporation oi Delaware No Drawing.Application December 13, 1949, Serial No. 132,806. In Great Britain May10, 1945 6 Claims. (Cl. 260-784) This invention relates to improvementsin the production of linear nitrogen-containing polymeric materials andis more particularly concerned with the production of polymers suitablefor the formation of filaments, films and plastic materials. Theapplicationis a continuation-inpart of our application S. No. 662,628filed April 16, 1946.

The polymers appear to be poly-4-amino-1.2.4-

triazoles. According to the invention, they are produced by heating adicarboxylic acid or an 'anhydride of a dicarboxylic acid withhydrazine,

salt of hydrazine with the dicarboxylic acid, for

example hydrazine sebacate.

The polymers produced are very resistant to hydrolysis either by alkalior acid, for example hydrochloric acid, and hence show little or notendency to depolymerisation. Many of them have melting points whichmake them suitable for the production of filaments for use in textilematerials, that is to say they have melting points above the usualironing temperatures.

The dicarboxylic acids may be those in which the two carboxylic groupsare the sole substituent radicles in a hydrocarbon chain, for examplesuccinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid,azelaic acid, sebacic acid and the higher dicarboxylic acids of thisseries, diphenic acid, phenylene 1.4-diacetic acid and similardicarboxylic acids of the aromatic series. In the above-mentionedaliphatic dicarboxylic acids, it is preferred to use polymethylenedicarboxylic acids, 1. e. acids of the general formula HOOC(CHz);|COOH,where n is more than 4', i. e. acids from pimelic acid upwards. Theinvention also includes the use of dicarboxylic acids containingsubstituents or hetero atoms which do not interfere with the reaction,for example diglycollic acid, N-methyl-imino-diacetic acid,thiodivaleric acid HOOC (CH2) 4.S.(CH2) 4COOH, and similar dicarboxylicacids containing unreactive atoms in the chain.

The condensation may be carried out by simple heating. Usuallytemperatures of the order of ZOO-300 0., and especially 230-280 C., are

suitable for the purpose. Heating may be carried out on the undilutedreagents or the reagents may be suspended or dissolved in a suitablediluent. The presence of water during the condensation is verybeneficial, at least in the initial stages, since it appears to preventor retard a tendency for the polymer to become resinous or soluble,possibly by cross-linking or some other side reaction. This water may beadded in the form of hydrazine hydrate or an aqueous solution ofhydrazine hydrate. The condensation is preferably carried out, at leastin the initial stages, in a closed vessel, though in the later stagesthe pressure that builds up may be wholly or in part released, and,further, towards the end of the condensation the pressure may be reducedto below atmospheric pressure. This final reduction of pressure to belowatmospheric pressure is not, however, necessary, and the wholecondensation may be carried out in a closed vessel with or withoutperiodic or continuous release of pressure, for example release ofpressure down to 300 lbs. per square inch.

The minimum proportion of hydrazine necessary to produce polymersresistant to hydrochloric acid varies somewhat with the temperature atwhich the condensation is carried out. For example, with sebacic acidand a condensation temperature of 190 C., 2.17 moles of hydrazine foreach mole of acid generally sufilce, while at 210 C. 2.21 moles ofhydrazine appear to be necessary and at 230 C. 2.33 moles. Probablythere are other factors which determine the minimum proportion ofhydrazine necessary, but simple trial is sufficient to ascertain such aminimum proportion. Generally it is advisable to use more than theminimum, for example the 10% excess of hydrazine (calculated on theweight of the dicarboxylic acid plus two moles of hydrazine) referred toabove.

While the invention includes the production of polymers of relativelylow molecular weight, it is mainly addressed to the production ofpolymers which have filmand filament-forming properties. It is foundthat the ability to form filaments usually sets in when an intrinsicviscosity of 0.30.4 is reached, as measured in a 1% solution of thepolymer in meta-cresol. For the best filaments the condensation is bestcarried to an intrinsic viscosity of at least 0.5-0.6, at which stagefilaments made from the polymers usually exhibit cold-drawingproperties, with consequent increase in their tensile strength measuredin grams per denier.

As indicated above, the polymers are extremely 3 stable to hydrolysingagencies and hence there is very little tendency for their viscosity todecrease. Some of them probably contain terminal hydrazide groups whichare capable of further condensation. Such a tendency to furthercondensation may be eliminated, or in other words the chain length ofthe polymer may be stabilised, by hydrolysing these terminal hydrazidegroups. For example the polymer may be heated with an aqueous solutionof hydrochloric acid or any other suitable mineral acid to split oif thehydrazine at the ends of the chains and thus constitute carboxylic acidgroups as the terminal groups. The polymer is then obtained in the formof a hydrochloride or similar salt, and the base may be recoveredtherefrom by suitable neutralisation of the acid. The polymer thenappears to be stable against increase in chain length.

The invention includes the production of filaments, films and otherarticles from the polymers produced as described above. The filamentsmay be produced by melt spinning, i e. by extruding a melt of thepolymer through suitable orifices. In general the temperature of thepolymer to be extruded should be some -30" above the melting point ofthe polymer. This melting. temperature may be modified to some extent,e. g. with a view to reducing any tendency to decomposition duringspinning at very high temperatures, by mixing the polymer with suitableproportions of plasticisers, for example sulfonamide plasticisers,phenolic plasticisers, urea and thiourea plasticisers and the like. Suchplasticisers may either be left in the produrts or may be partially orcompletely extracted therefrom. Filaments may also be produced by wet ordry spinning methods from solutions in suitable solvents, for exampleformic acid or acetic acid or phenolic solvents.

The filaments so formed may, if the polymer be of sufilciently highmolecular weight, be drawn out at comparatively low temperatures, oreven at atmospheric temperature, to very fine filaments having hightenacity and good elasticity. The resulting filaments may then be usedfor any of the purposes to which artificial silks have in the past beenapplied. Generally the products have an afilnity for the dispersedinsoluble type of dyestuif now generally applied to cellulose acetate.They also exhibit an amnity for the acid wool colours.

While the invention is especially directed to the manufacture andapplication of fibre-forming polymers, it is not limited thereto andembraces the production of similar polymers suitable, for example, foruse as softening agents, coatings, film-forming substances, and thelike. Moreover, for these applications the polymers of the presentinvention may be mixed with other fibre-forming, film-forming or lacquersubstances or other ingredients, for example cellulose acetate,aceto-butyrate, butyrate and acetostearate, ethyl cellulose, oxyethylcellulose, oxyethyl cellulose acetate, benzyl cellulose and othercellulose derivatives, plasticizers or softening agents, dyestufis,pigments and the like.

The following examples illustrate the invention but are not to beconsidered as limiting it.

Example 1 4 pressure by release to about 250 lbs. The product had amelting point of about 250 C. and an intrinsic viscosity of 0.51, andwas readily capa-' ble of yielding filaments from the melt which couldbe colddrawn.

Example 2 A dope was prepared by dissolving 450 gms. of the polymerprepared according to Example 1 above in parts of orthophenyl phenol and200 parts of meta-cresol under nitrogen. The cresol was then allowed toboil ed. The product cooled to a hard mass. The mixture was thenintroduced into a melt spinning crucible fitted just in front of thespinneret with a filter screen of one layer of 150 mesh Phosphor bronzegauze and two layers of 300 mesh Phosphor bronze gauze. The spinnert hada diameter of 0.2 mm. The spinning crucible was heated by anelectrically heated lead bath to a temperature of 250 C. A nitrogenpressure of 300 lbs. per square inch was applied and the extrudedfilaments wound up on a cheese former. The product had an extremely highlustre and exhibited good cold-drawing propert es.

Example 3 100 parts by weight of sebacic acid and parts by weight of 50%aqueous hydrazine hydrate were heated together in an autoclave for 2hours at 260 C. and then for a further 2 hours at the same temperaturewhile releasing the pressure to 500 lbs. per square inch. The producthad an intrinsic viscosity of 0.36 and yielded long filaments from themelt.

Example 4 including a melting point of 256-257 C. and an' intrinsicviscosity of 0.58.

Example 5 100 parts by weight of sebacic acid were heated in anautoclave with 75 parts by weight of 60% aqueous hydrazine under thefollowing temperature and pressure conditions, the autoclave remainingclosed throughout:

(a) At 140 C. for 2 hours. lbs. per square inch. (b) At 210 C. for 6hours. 250 lbs. per square inch. (c) At 230 C. for 14 hours. Pressurerecorded 600 lbs. per square inch.

The product was a white solid with fibre-forming properties, a meltingpoint of 264 C. and an intrinsic viscosity of 0.57. Its nitrogen contentwas 28.0%.

All the above polymers from sebacic acid were insoluble in water,methanol, chloroform, acetone and benzene, and soluble in cresol and informic acid.

Pressure recorded Pressure recorded Example 6 117 parts by weight ofthiodivalerlc acid HO0C.(CH2 4.S.(CH2)4.COOH and 96 partsby weight of60% aqueous hydrazine were heated in an autoclave for 2 hours at C., 1hour at 200 C. and then 1% hours at 220 C. The prodnot was a white solidof melting point -155' 0., capable of forming long line filaments. Itwas insoluble in water, acetone. chloroform and benzene, slightlysoluble in methanol and soluble in cresol and in formic acid. Itssulphur content was 14.0%.

Example 7 Example 8 20 parts by weight of pimelic acid and 20 parts byweight of 60% aqueous hydrazine were heated in an autoclave for hours at230 C. At the end of this treatment, during which the pressure reached1000 lbs. per square inch, the pressure was released down to 500 lbs.per square inchand the polymer heated for another hour at 230 C. Themelting .point of the polymer was 258 C. and its intrinsic viscosity0.43. It was insoluble in acetone and benzene and soluble in cresol andin formic acid.

Example 9 To 50 parts by weight of monomeric adipic anhydride 30%aqueous hydrazine was slowly added. A vigorous reaction took place andwhen the amount of hydrazine added was rather more than half a mole foreach mole of initial adipic anhydride a somewhat yellowish solidseparated out. 'lj'his solid was isolated and washed first with 1.4-dioxane and then with cold water. By this means the yellowishcolouration was removed and the resulting product was almost pure white.44 parts'o'f this washed solid and 60 parts of 40% aqueous hydrazinewere then heated in a closed autoclave for 3 hours at 210 C. withoutrelease of pressure. The maximum pressure recorded was 280 lbs. persquare inch. The product was a. granular solid, slightly off white, andhad a melting point of 275 C. Its solubility properties were the same asthose of the polymer produced in Example 7 above. Its nitrogen contentwas 35.4%. Having described our invention, what we desire to secure byLetters Patent is:

1. Process for the production of a nitrogen-containingpolymer, whichcomprises heating a reaction mixture containing a dicarbo lic reagentselected from the group consisting of licarboxylic acids, free fromreactive groups other! than the car-boxy groups, and their anhydridewandcontaining hydrazine, the total amount rfi'liydrazlne in the reactionmixture being more than two molesfor each mole of dicarboxylic acid andbeing suilicient to produce a polymer resistant to hydrochloric acid,and continuing the heating until the polymer is produced.

2. Process for the production of a nitrogen-containing polymer, whichcomprises heating a reaction mixture containing a dicarboxylic reagentselected from the group consisting of dicarboxylic acids, free fromreactive groups other than the carboxy groups, and their anhydrides, andcontaining hydrazine, the total amount of hydrazine in the reactionmixture being more than two moles for each mole of dicarboxylic acid andbeing sufliclent to produce a polymer resistant to hydrochloric acid,and continuing the heating until the polymer has fibre-formingproperties.

3. Process for the production of a nitrogen-containing polymer, whichcomprises heating a reaction mixture containing a dicarboxylic reagentselected from the group consisting of dicarboxylic acids, free fromreactive groups other than the carboxy groups, and their anhydrides, andcontaining hydrazine and water, the total amount of hydrazine in thereaction mixture being more than two moles for each mole of dicarboxylicacid and being sufilcient to produce a polymer resistant to hydrochloricacid, and continuing the heating until the polymer is produced.

4. Process for the production of a nitrogen-containing polymer, whichcomprises heating a reaction mixture containing a dicarboxylic acid ofthe formula HOOC(CH2)nCOOH, where n is an integer more than 4, withhydrazine and water, the total amount of hydrazine being more than twomoles for each mole of dicarboxylic acid and being suflicient to producea polymer resistant to hydrochloric acid, and continuing the heatinguntil the polymer is produced.

5. Process for the production of a nitrogen-containing polymer, whichcomprises heating a reaction mixture containing a dicarboxylic acid ofthe formula HOOC(CH2)1|COOH, where n is an integer more than 4, withhydrazine and water, the total amount of hydrazine being more than twomoles for each mole of dicarboxylic acid and being suflicient to producea polymer resistant to hydrochloric acid, and continuing the heatinguntil the polymer has fibre-forming properties.

6. Process for the production of a nitrogen-containing polymer, whichcomprises heating a reaction mixture containing sebacic acid withhydrazine and water, the total amount of hydrazine being more than twomoles for each mole of sebacic acid and being sufficient to produce apolymer resistant to hydrochloric acid, and continuing the heating untilthe polymer has fibreforming properties.

HAROLD BATES.

JAMES WOTHERSPOON FISHER.

EDWARD WILLIAM WHEA'I'LEY.

No references cited.

1. PROCESS FOR THE PRODUCTION OF A NITROGENCONTAINING POLYMER, WHICHCOMPRISES HEATING A REACTION MIXTURE CONTAINING A DICARBOXYLIC REAGENTSELECTED FROM THE GROUP CONSISTING OF DICARBOXYLIC ACIDS, FREE FROMREACTIVE GROUPS OTHER THAN THE CARBOXY GROUPS, AND THERE ANHYDRIDES, ANDCONTAINING HYDRAZINE THE TOTAL AMOUNT OF HYDRAZINE IN THE REACTIONMIXTURE BEING MORE THAN TWO MOLES FOR EACH MOLE OF DICARBOXYLIC ACID ANDBEING SUFFICIENT TO PRODUCE A POLYMER RESISTANT TO HYDROCHLORIC ACID,AND CONTINUING THE HEATING UNITL THE POLYMER IS PRODUCED.